1. Field of the Invention
The present invention relates to a controller of a mobile object such as a legged mobile robot, and an estimator for estimating a position and posture of a floor surface on which the mobile object moves.
2. Description of the Related Art
In motion control of a mobile object such as a legged mobile robot that moves on a floor surface by moving a plurality of leg links (e.g. repeatedly landing and lifting each leg link) connected to a body, each leg link's joints are basically driven so that an actual motion of the mobile object follows a desired motion of the mobile object.
Typically, the desired motion is generated so as to satisfy kinetic requirements (requirements such as the ZMP existing within a supporting polygon) on a supposed floor surface that is set to represent an actual floor surface. However, a shape error and the like of the supposed floor surface, which is used for generating the desired motion, from the actual floor surface can cause the actual motion of the mobile object to deviate from the desired motion. In such a case, the mobile object tends to lose its posture.
As a technique for preventing this, a compliance control technique proposed by the applicant of the present application in Japanese Patent No. 3629133 (hereafter referred to as Patent Document 1) as an example is conventionally known. In this compliance control technique, while observing a floor reaction force actually acting on a bipedal walking robot, a desired position and posture of a distal end (foot) of each leg link are corrected so that an actual floor reaction force moment generated about a desired total floor reaction force central point follows a desired moment for restoring the bipedal walking robot's upper body posture to a desired posture. The amount of displacement of each joint of the leg link is controlled according to the corrected desired position and posture.
Moreover, a technique of estimating an inclination angle of an actual floor surface in a mobile environment of a legged mobile robot is conventionally proposed by the applicant of the present application in Japanese Patent No. 3024028 (hereafter referred to as Patent Document 2) as an example.